The Queen has issued a hilarious takedown of Barack and Michelle Obama in the only way the monarch knows how: with the utmost respect and brimming with politeness.

Her hilarious reaction was encouraged by her grandson, Prince Harry, in response to being playfully ridiculed by the US President and First Lady threatening American domination of the Invictus Games, which are held for wounded, injured or sick servicemen and women.

In the royals' video, Prince Harry receives a video message from Mrs Obama that he decides to watch with his gran.

"Hey Prince Harry. Remember when you told us to bring it at the Invictus Games? Be careful what you wish for," the Obamas, with arms folded, say before three servicemen behind them perform the mic drop action.

Back in the royal sitting room, Prince Harry looks somewhat unnerved before his grandmother swoops in with her cracking one-liner.

"Oh really? Please," she says in the most dismissive English civility one can muster, before her grandson turns to the camera and issues his own mic drop complete with a "boom".

The candid video is a rare entry into humour for Queen Elizabeth, who also famously entertained when she appeared in the opening ceremony of the London Olympics in 2012 alongside Daniel Craig as James Bond.